1. Field of the Invention:
The present invention relates to a slide fastener stringer.
2. Prior Art:
Durable functioning of slide fasteners requires that a thickened stringer tape edge be rigid and uniform enough to be firmly gripped by and support stably the attachment legs of coupling elements against displacement on or removal from the tape edge under severe forces. One well known expedient which has been proposed to meet such requirements is stranded yarns mounted on and along a fastener tape edge for supporting coupling elements thereon. However, the stranded yarns are liable to be easily split, crushed, or otherwise deformed when pressed and frequently fail to provide sufficient mechanical strength to stabilize metallic fastener elements staked on or plastic fastener elements injection-molded on the tape edge (FIG. 9). With this prior arrangement, the mounted fastener elements tend to become loose in attachment and irregular in posture during use, resulting in malfunctioning of the slide fastener.
Another element-carrying thickened tape edge comprises a central core surrounded by a weft knit tube. The weft knit tube is subject to radial expansion and cannot fasten the central core radially inwardly. Thus, the tape edge reinforcement is poor in integrity and stability.